8 Найдите сумму: a) \(\frac{8}{13} + \frac{3}{13}\); б) \(\frac{31}{60} + \frac{29}{60}\); в) 18+ \(\frac{4}{19}\); г) 23+ \(\frac{9}{10}\); д) 2 \(\frac{7}{9} + \frac{8}{9}\); e) 15 \(\frac{8}{11} + 4 \frac{3}{11}\); ж) 4 \(\frac{1}{2} + 3 \frac{1}{4}\); з) 5 \(\frac{1}{7} + 3 \frac{20}{21}\);

Решение:

1. a) \(\frac{8}{13} + \frac{3}{13} = \frac{8+3}{13} = \frac{11}{13}\)

Ответ: \(\frac{11}{13}\)

1. б) \(\frac{31}{60} + \frac{29}{60} = \frac{31+29}{60} = \frac{60}{60} = 1\)

Ответ: 1

1. в) \(18+ \frac{4}{19} = 18 \frac{4}{19}\)

Ответ: \(18 \frac{4}{19}\)

1. г) \(23+ \frac{9}{10} = 23 \frac{9}{10}\)

Ответ: \(23 \frac{9}{10}\)

1. д) \(2 \frac{7}{9} + \frac{8}{9} = 2 + \frac{7}{9} + \frac{8}{9} = 2 + \frac{15}{9} = 2 + \frac{5}{3} = 2 + 1 \frac{2}{3} = 3 \frac{2}{3}\)

Ответ: \(3 \frac{2}{3}\)

1. е) \(15 \frac{8}{11} + 4 \frac{3}{11} = (15 + 4) + (\frac{8}{11} + \frac{3}{11}) = 19 + \frac{11}{11} = 19 + 1 = 20\)

Ответ: 20

1. ж) \(4 \frac{1}{2} + 3 \frac{1}{4} = 4 + \frac{1}{2} + 3 + \frac{1}{4} = 7 + \frac{1}{2} + \frac{1}{4} = 7 + \frac{2}{4} + \frac{1}{4} = 7 + \frac{3}{4} = 7 \frac{3}{4}\)

Ответ: \(7 \frac{3}{4}\)

1. з) \(5 \frac{1}{7} + 3 \frac{20}{21} = 5 + \frac{1}{7} + 3 + \frac{20}{21} = 8 + \frac{3}{21} + \frac{20}{21} = 8 + \frac{23}{21} = 8 + 1 \frac{2}{21} = 9 \frac{2}{21}\)

Ответ: \(9 \frac{2}{21}\)